Along with the rapid spread in popularity of electronic devices—foremost smartphones and tablet computers—in recent years, the demand for touchscreens that detect the location where a human finger or a stylus pen has touched the screen has been especially on the rise. A known touchscreen of this sort is the resistive-film type of touchscreen in which two resistive-film sheets are arranged in opposition and placed in a touch surface, wherein from the value of the resistance when a user has touched the touch surface, the touch position is detected. A known example of a method of inspecting this sort of resistive-film type of touchscreen is Patent Document 1.
Meanwhile, in recent years, touchscreens of the capacitive type—in which transparent electrodes arranged in the form of a grid are placed in the touch surface, and based on the capacitance produced when a user touches the screen with his or her finger(s), the touched position is detected—have come into widespread use. With the capacitive type of touchscreen, two-dimensional x-y coordinates are established in the face of the screen, and a plurality of transparent electrodes extending in the x direction and a plurality of transparent electrodes extending in the y direction, corresponding to the x-y coordinates, are arranged in opposition, electrically isolated from each other, on a transparent substrate such as, e.g., glass.